In vitro diagnostics (IVD) allows labs to assist in the diagnosis of disease based on assays performed on patient fluid samples. IVD includes various types of analytical tests and assays related to patient diagnosis and therapy that can be performed by analysis of a liquid sample taken from a patient's bodily fluids, or abscesses. These assays are typically conducted with automated clinical chemistry analyzers (analyzers) onto which fluid containers, such as tubes or vials containing patient samples have been loaded. The analyzer extracts a liquid sample from the vial and combines the sample with various reagents in special reaction cuvettes or tubes (referred to generally as reaction vessels). In some conventional systems, a modular approach is used for analyzers. A lab automation system can shuttle samples between one sample processing module (module) and another module. Modules may include one or more stations, including sample handling stations and testing stations (e.g., a unit that can specialize in certain types of assays or can otherwise provide testing services to the larger analyzer, which may include immunoassay (IA) and clinical chemistry (CC) stations. Some traditional IVD automation track systems comprise systems that are designed to transport samples from one fully independent module to another standalone module. This allows different types of tests to be specialized in two different stations or allows two redundant stations to be linked to increase the volume of sample throughput available. These lab automation systems, however, are often bottlenecks in multi-station analyzers.
In an exemplary prior art system, a friction track, much like a conveyor belt, shuttles individual carrier mechanisms, sometimes called pucks, or racks of containers between different stations. Samples may be stored in sample containers, such as test tubes that are placed into a puck by an operator or robot arm for transport between stations in an analyzer along the track. This friction track, however, can only move in one direction at a time and any samples on the track will move in the same direction at the same speed. When a sample needs to exit the friction track, gating/switching can be used to move individual pucks into offshoot paths, which may be called sidecars. A drawback with this set up is that singulation must generally be used to control the direction of any given puck at each gate and switch. For example, if two pucks are near one another and only one puck should be redirected into an offshoot path, it becomes difficult to control a switch so that only one puck is moved into the offshoot path and ensure that the proper puck is pulled from the friction track. This has created the need in many prior art systems to have pucks stop at a gate so that individual pucks can be released and switched one at a time at each decision point on a track. Furthermore, additional friction tracks rely on optical identification of samples via barcodes at any decision points on the automation track. This may require a slow mechanical stop, rotate, and check process that limits the number of samples that may pass a singulated decision point.
Hard singulation slows down the overall track and increases traffic jams within the track. This leads to the need for physical queues within the track. Much like traffic on a road, traffic on the track causes an accumulation of slow-moving pucks because most of the time spent in transit during operation can be spent waiting through a line at a singulation point for switching by a gate. This leads to inefficiency in transit. Ultimately for a high volume analyzer, a substantial amount of time for each sample is spent waiting in queues at the gates on the friction track. This increases the latency experienced by each sample. Latency can be a problem for certain types of samples, such as whole blood samples, which can begin to separate or coagulate if the sample sits in the sample tube for too long.
Because pucks traditionally stop to be routed, handled, and processed, samples in prior art systems find themselves waiting in several queues before all processing on a sample is completed. These queues can grow to be quite large as the number of samples to be handled grows. Most conventional lab automation tracks maintain FIFO processing queues to buffer samples that are waiting to be processed by modules (analyzers or pre/post analytic devices). These buffers allow the track to process tubes at a constant rate even though the modules create bursts of demand.
Another problem with long queues and traffic on the friction track is the issue of handling STAT samples. A STAT sample is a sample that an operator wishes to have moved to the front of the line so that results for that sample can be returned quickly. For example, in a hospital with an emergency room, test results may be urgent for a patient awaiting treatment. In prior art friction track systems with long queues, the entire queue often must be flushed to make way for the STAT sample. This can undo several minutes worth of sorting of samples and can increase the overall latency experienced by non-STAT samples. When a STAT sample is introduced to the track, it must either wait for all of the samples in the queue to be processed, or the entire queue must be flushed back to the main track in order to allow the STAT to be processed immediately. If the queue is flushed, then the analyzer will have to abandon any work it may have already done to prepare to aspirate the queued samples, such as preparing a cuvette or aspirating a reagent. Flushing the queue is also disruptive to the automation system. A large number of samples with unprocessed work will flood onto the main track and have to be routed. Each sample must travel the complete length of the track loop in order get back to the analyzer and reenter the queue.